20409409 has 4 divisors (see below), whose sum is σ = 20418480. Its totient is φ = 20400340.

The previous prime is 20409383. The next prime is 20409437. The reversal of 20409409 is 90490402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90490402 = 2 ⋅45245201.

It is a cyclic number.

It is not a de Polignac number, because 20409409 - 2¹³ = 20401217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20409209) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1674 + ... + 6604.

It is an arithmetic number, because the mean of its divisors is an integer number (5104620).

Almost surely, 2^20409409 is an apocalyptic number.

It is an amenable number.

20409409 is a deficient number, since it is larger than the sum of its proper divisors (9071).

20409409 is an equidigital number, since it uses as much as digits as its factorization.

20409409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9070.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 20409409 is about 4517.6773899870. The cubic root of 20409409 is about 273.2814434845.

It can be divided in two parts, 2040 and 9409, that added together give a square (11449 = 107²).

The spelling of 20409409 in words is "twenty million, four hundred nine thousand, four hundred nine".